My guess is that Porter felt that Elmore was more likely to get on base, or at least make contact, than Brett Wallace. Since it was the last out of the game and the Twins' closer was on the mound, I think he was trying to go with the higher liklihood of making contact and getting on base. Wallace is striking out 33% of the time, walking 6% of the time, and on top of that, facing a LH closer. Elmore is walking 10% and striking out 16%, and has been a contact type hitter in the minors. Of course, I can see the argument on the other side that Wallace has a chance of hitting the ball out of the yard. Given the situation (runner on base, 2 outs in the 9th, lefty closer), I can see why he goes with Elmore over Wallace.